This PR should improve tests stability and transparency (when it comes
to unsupported tests). List of changes:

- switched from `[[intel::reqd_sub_group_size]]` to
  `[[sycl::reqd_sub_group_size]]` attribute;
- removed uses of deprecated `device::has_extension` API: there is no need
  for that check, because, `[[sycl::reqd_sub_group_size]]` is a core SYCL
  2020 functionality;
- simplified helpers to remove unnecessary extra arguments which could be
  inferred otherwise;
- updated `REQUIRES` directives to include required sub-group size
  requirements in there. Adjusted calls to `launchInlineASMTest` helper to
  consistently pass required sub-group size in there as well;

…esh-inline-asm-e2e-tests